Signaling system



March 0- 0.12. BRANSON ET AL 2,192,961

SIGNALING SYSTEM Filed Feb. 11, 1939 FIG/ ? IIIIW 5 l3 /7 I /5 J kW/u f m T- 4 T /4 f m g ,5

I .D.E.BRANSON 'EE WATSON Patented Mar. 12, 1940 UNITED STATES SIGNALING SYSTEM David E. Branson, River Edge, N. J., and Edward F. Watson, Larchmont, N. Y., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application February 11, 1939, Serial No. 255,820

10 Claims.

This invention relates to telegraph systems and particularly to systems wherein a common transmission channel is provided for a plurality of stations, any one of which may broadcast mess sages into said channel for simultaneous reception by all of said stations. This invention is an improvement on the system disclosed in Patent 2,111,684 granted March 22, 1938, to C; R. Walker.

l" Asin the Walker patent a series of stations is arranged in a circuit which is closed upon itself in a ring and transmission is always in a single direction so that the message transmitted by one station traverses all the others and is finally received by the station which transmits it. Due to the length of the circuit and the inclusion of repeaters of various types and other electrical devices, such a circuit has a definite propagation time which may be scveral seconds 2 and hence the ring must be broken at the transmitting station to prevent a returning message from interfering with that being transmitted. Heretofore the ring was broken by a manual operation and an elaborate time schedule had to be established and rigidly observed to prevent the ring ever being completely closed. An object of the present invention is to render this operation automatic. The propagation time of the circuit which is readily obtained by completely closing the ring and then observing the speed with which a signal travels around the circuit is determined and a means whichis slow releasing for a period somewhat longer than such propagation time is provided. This slow-releas- 35 ing means is provided to open the ring and is made responsive to the signals from the transmitting apparatus at a station. Hence, so long as a station is transmitting and for a period somewhat longer than the propagation time of 40 the ring thereafter, the ring is opened. Since complete closure does not take place until the last impulse sent has completely traversed the ring, a continuously traveling signal is automatically prevented.

' Another object of the invention is to provide means in a circuit of this nature responsive to a standard practice break signal used in other types of circuits. Accordingly, a feature of the invention is a slow-acting means unresponsive to 50 incoming signals of normal length but responsive to abnormal length signals such as a break signal whereby another station may signal the transmitting station that it is desired to use the ring presumably for more important messages. fifi'such means will automatically stop transmis sion at the transmitting station and close through the ring thereat.

Still another object is to provide means to give an alarm indicating a line failure at a station adjacent to the section of the line in trouble. 5 Accordingly. another feature of the invention is a means responsive to a prolonged open circuit similar to but of much longer duration than a break signal for operating an alarm. Each station circuit then in accordance with these features will respond to an open circuit condition at its incoming terminal but will in time automatically present a closed circuit condition at its outgoing terminal. However, the closed cirv cuit condition presented by the station just preceding the point of the trouble cannot be transmitted to the station next adjacent thereto and hence an open circuit condition will be presented to the incoming terminal of this next adjacent station and so an alarm will be given at only this station.

In the drawing:

Fig. 1 is a schematic representation of the completesystem in which the invention is employed; and v I Fig. 2 is a circuit diagram showing the details of a station circuit embodying the present invention.

In Fig. 1 there is shown a ring circuit including rectangles l, 2, 3; 4, 5 and 6 which represent station circuits at as many different cities, such, for instance, as New York, Boston, Albany. Buffalo, Pittsburgh and Philadelphia. There is also shown in the circuit a rectangle l and an other rectangle 8 which may indicate repeaters or other time consuming transmission apparatus.

To each station circuit at the different points in the'ring one or more separate stations may be connected. The transmitting contacts 9 and the magnet ll] represent in the usual form a sub- 40 scribers teletypewriter station. The transmitting contacts II and the magnet l2 represent a similar subscribers station connected to the same station circuit I. i

Fig. 2 represents a station circuit such as in one of those represented generally by the rectangles to 6, inclusive, Conductors l3 and [4 represent the incoming terminal and conductors l5 and 16 represent the outgoing terminal. Marking pulses coming in on conductors I3 and M will move the armature of relay I l to its right-hand or marking contact and spacing impulses likewise will move the armature to its lefthand or spacing contact. The marking and spac-- ing impulses from the armature of relay l1 flow over conductor 18 through the back contact and outer, left-hand armature of relay I9, the back contact and armature of relay 20 through the upper winding of relay 2|, the lower winding of relay 22 and thence through the circuits of subscribers stations 23 and 24 to battery. Relay 22 will respond and will open and close the circuit of conductors l5 and I6 representing the outgoing terminal and thus create opened and closed conditions denoting marking and spacing pulses transmitted beyond this station. The magnet 26 of subscribers station 24 will respond and record any messages being transmitted over the ring. Magnet of subscribers station 23 will also respond to the action of receiving relay l1 so that any message being transmitted over the ring will also be recorded at this station. Relay 2| does not respond in this circuit.

When either of subscribers station 23 or 24 transmits, relay 2i responds and this in turn causes the operation of delay 20 which therefore effectively opens the ring circuit at its armature. This relay is slow to release and may be designed to be slightly greater in its releasing time than the propagation time of the entire ring circuit. During the time relay 2!] is operated it holds steady marking potential on the upper winding of relay 2i and the lower winding of relay 22 so that either of the stations 23 and 2 may transmit uninterruptedly.

Under normal conditions when a steady marking impulse is received over conductors l3 and M or while regular transmission is taking place no spacing impulse of greater than signal length is received, relay l9 which is slow to operate, does not move its armatures. This is also true while either one of the subscribers station 23 or 24 is transmitting, since the transmission eventually returns on the ring and manifests itself in conductors l3 and It and operates relay ll.

Relay i9 is arranged to operate on a signal similar to a break but of. longer duration. While the energizing circuit of relay [3 is closed on a break signal this relay is timed not to respond until a period of five seconds for example has elapsed andthus this relay differentiates between a normal break signal and a similar but longer signal denoting an unstandard condition.

If some station before conductors i3 and M transmits a prolonged spacing signal or if trouble occurs and manifests itself as a prolonged spacing signal, then relay 19 will become operated and thus will connect marking battery through the front contact and outer armature of relay is and thence to the relay 2!, moving the armature of relay 2! to its marking contact, provided the circuit of this relay is properly closed through the transmitting contacts of subscribers stations 23 and 24. Relay [9 will also close a circuit to cause the operation of an alarm 21.

If, during transmission from one of the stations 23 and 24 and while relay 2% is operated, a break signal is transmitted by some other station in the ring, relay I! will move its armature to its spacing contact so that relay 2!), which has heretofore been periodically energized by the armature of relay 2| which is connected to a current source of spacing potential, will release its armature. This prolonged spacing or break signal will then manifest itself at stations 23 and 24 and thus the subscribers will be notified that a break is being made by some other subscriber and they will act accordingly, that is close the circuit by ceasing to transmit.

If this break signal persists longer than normal and thus denotes an unstandard condition, relay l9 will operate and place marking potential on the line again so as to close the circuit through conductors l5 and I6 and at the same time operate the alarm Zl. The marking condition on conductors I5 and I6 will then be passed around the ring circuit to the station making the break. If a break is made through line failure then through the means described the circuit will adjust itself so that in time only the station next adjacent the break will be affected and trans mission may proceed around the remaining part of the circuit. For instance, if a break occurred in conductor 13 just to the left of the relay I! then it would be possible for subscribers stations 23 and 24 to transmit to all the other stations in the ring but it would not be possible for any one of the stations to transmit to the subscribers stations 23 and 24.

Various arrangements of the subscribers sta tions may be had. For instance,, subscribers" station 24 has its transmitting contacts and its receiving means both in the same circuit. In such a case the receiving means will record transmitted messages (generally referred to as local copy) but will not record what is transmitted from its associated transmitting contacts after this has been transmitted completely around the ring. On the other hand, the receiving means 25 of the subscribers station 23 will not make local copy but will record only messages coming in on the receiving terminals l3 and it. If it were so desired a subscribers station could be equipped with both types of receiving means so that local copy as well as the message traversing the entire ring could be recorded.

With subscribers stations such as 23 at New York and Buffalo for example a two-way conversation could be carried on because what is transmitted from New York will be recorded at Buffalo as well as at Boston and Albany while simultaneously therewith a subscriber at Buffalo could be transmitting to New York as well as to Pittsburgh and Philadelphia.

Whatis claimed is:

1. In a signaling system, a station circuit having incoming and outgoing terminals normally connected for through transmission, transmitting apparatus and means responsive to signals from said transmitting apparatus for opening said normal connection between said terminals for the over-all period of the successive transmission of a plurality of signals.

2. In a signaling system, a station circuit having incoming and outgoing terminals normally connected for through transmission, receiving apparatus connected to said incoming terminal, transmitting apparatus and means responsive to signals from said transmitting apparatus for opening said normal connection between said w terminals for the over-all period of the successive transmission of a plurality of signals.

3. In a signaling system, a station circuit having incoming and outgoing terminals normally connected for through transmission, transmitting apparatus, and means responsive to signals from said transmitting apparatus for opening said normal connection'between said terminals for the over-all period of the successive transmission of a plurality of signals, said last means including slow-acting means for maintaining said open connection for a predetermined period after said transmitting apparatus has ceased to operate.

l. A signaling system comprising a plurality of stationcircuits connected in a closed ring,

each said station circuit having incoming and outgoing terminals normally connected for through transmission, transmitting apparatus, and means responsive to signals from said transmitting apparatus for opening said normal connection between said terminals for the over-all period of the successive transmission of a plurality of signals, said last means including slowacting means for maintaining said open connection for a period greater than the propagation time of said closed ring after said transmitting apparatus has ceased to operate.

5. A signaling system comprising a plurality of stations so connected that any one station transmitting will receive the transmitted message through the remainder of all of said stations, a station circuit for each said station having incoming and outgoing terminals normally connected for through transmission, transmitting apparatus and means responsive to signals from said transmitting apparatus for opening said normal connection between saidterminals, said last means being slow acting by a period greater than the time taken for a transmitted signal to traverse said stations and reach said receiving apparatus.

6. In a signaling system, a station circuit having incoming and outgoing terminals normally connected for through transmission, transmitting apparatus, means responsive to signals from said transmitting apparatus for opening said normal connection betweensaid terminals, and means responsive to signals received at said incoming terminal, said last means being slow acting and responsive only to signals of more than normal length, said last means operating to render said first means inefiective.

'7. In a signaling system, a station circuit having incoming and outgoing terminals normally connected for through transmission, transmitting apparatus, means responsive to' signals from said transmitting apparatus for opening said normal connection between said terminals, said means automatically maintaining said open connection for a predetermined period after said transmitting apparatus has ceased to operate and slow-acting means responsive to signals of greater than ordinary length connected to said incoming terminal for disabling said first means.

8. A signaling system comprising a series of stations in a closed ring, each said station having incoming and outgoing terminals normally connected for through transmission, transmitting apparatus, means responsive to signals from said transmitting apparatus for opening said normal connection between said terminals, said means automatically maintaining said connection open for a time greater than the propagation time of said closed ring, and means connected toysaid incoming terminal unresponsive to normal signals but responsive to a signal of greater than normal length for disabling said first means.

9. In a signaling system, a station circuit having incoming and outgoing terminals normally connected for through transmission, transmitting apparatus, means responsive to signals from said transmitting apparatus for opening said normal connection between said terminals and for automatically maintaining said open circuit for a predetermined time after said transmitting apparatushas ceased to operate, means connected to said incoming terminal unresponsive to incoming signals of normal length but responsive to a signal of more than ordinary length to disablesaid first means, an alarm and slow-acting means responsive after a predetermined period to said last means for operating said alarm.

10. A signaling system comprising a series of stations in, a closed 'ring, each said station having incoming and outgoing terminals normally connected for through transmission, transmitting apparatus, means responsive to signals from said transmitting apparatus for opening said normal connection between said terminals, said means being slow releasing, means connected to said incoming terminal unresponsive to incoming signals of normal length but responsive to an open circuit maintained for a period greater than the normal length of incoming signals to disable said first means so as to transmit a closed circuit signal from said outgoing terminal, an alarm and slow-acting means responsive after a predeterminedperiod to said open circuit responsive means for operating said alarm, whereby an open circuit in said closed ring will eventually operate said alarm in the station adjacent to said break and will cause a steady closed circuit condition at all other said stations in said closed ring.

DAVID E; BRANSON. EDWARD F. WATSON. 

